Non-exuding rubbers



United States Patent ABSTRACT OF THE DISCLOSURE Vulcanizates preparedfrom high-rosin rubber compositions have not proved entirelysatisfactory because the rosin has a tendency to exude from thevulcanizate upon aging. A material such as .triethanolamine,n-octylamine, 'diethanolamine, morpholine, diphenylgu-anidine,hexamethylenetetramine, a rosin amine and mixtures thereof is added tohigh-rosin rubber compositions prior to vulcanization to eliminate thistendency of rosin to exude.

This application is a continuation-in-part of applica tion Ser. No.416,609, filed Dec. 7, 1964, now abandoned.

This invention relates to the rubber art, both natural rubber andsynthetic rubber. Particularly, this invention relates to novelvul-canizable rubber compositions extended with rosin and the likerubber extenders and to vulcanizates prepared therefrom.

Recently, rosin, both modified and unmodified, has been employed as anextender for rubber such as the commercially available synthetic rubberSBR derived by the copolymerization of styrene and 'butadiene.Rosin-extended rubber, also referred to as high-rosin rubber, hasimproved tensile strength and improved resistance to abrasion.

High-rosin rubber will contain, by weight, from about to 100 parts ofrosin for each 100 parts of rubber. Vulcanizates prepared fromhigh-rosin rubber compositions have not proved entirely satisfactorybecause the rosin has a tendency to exude from the vulcanizate uponaging. Thus, for example, disproportionate-d rosin has exuded from avulcanizate prepared from a rubber composition comprised of, by weight,'20 parts of disproportionated rosin for each 100 parts of rubber. Thisexudation, also referred to in the art as blooming, of rosin affectsadversely the appearance, tack, and other properties normally desired ina vuloanizate.

In accordance with this invention, it has been determined that thistendency of rosin to exude from highrosin rubber vulcanizates can beeliminated substantially by incorporating in the high-rosin rubbercomposition, prior to vulcanization, a relatively small amount of anamine selected from the group consisting of triethanolamine,n-octylamine, diethanolamine, morpholine, diphenylgu-anidine,hexamethylenetetramine, a rosin amine, and mixtures of two or more.Suitable rosin amines, and their method of preparation, are disclosedand escribed in U.S. Patent No. 2,491,916, reference to which is herebymade. Suitable rosin amines include N Wood rosin amine,hydroabietylamine, and dehydroabietylamine. The rosin amines can beprepared from Wood rosin, gum rosin, or tall oil rosin, modified orunmodified, or the pure acids contained therein such as abietic acid andpimaric acid or mixtures of the pure acids. Rosin amines can be preparedalso from polymerized rosin. The amine additive is sometimes referred tohereinafter as an anti-blooming agent.

The base composition of this invention will be comprised of (A) a rubbercomponent such as natural rubher, a synthetic rubber, mixtures ofnatural rubber and synthetic rubber, and mixtures of two or moresynthetic rubbers, (B) an extender for the rubber component se- :lectedfrom the group consisting of a rosin extender, a substantially petroleumhydrocarbon-insoluble pine wood resin, and mixtures of two or more, and(C) an antiblooming agent as above defined.

The amount of extender employed will be in an amount of from about 20parts to 100 parts by weight for each 100 parts by weight of rubbercomponent employed.

The amount of amine additive or anti-blooming agent employed will dependon the nature of the amine itself and on the amount of extenderemployed. The minimum amount Will be that required to prevent exudationof the extender employed. The maximum amount that can be employed willbe limited by the effect the amine additive has on the softening of therubber and the activating effect of the amine which, if used in toolarge an amount, will lead to pre-curing or scorching of thecomposition. The optimum amount will usually be that required just toovercome the cure-inhibiting effect of the extender employed, whichamount will he usually slightly greater than the minimum amount neededto prevent blooming. For example, the amount of tri-ethanolaminerequired to prevent exudation of disproportionated rosin from avulcanizate prepared from a rubber composition comprised thereof will beabout 5% by weight, based on the weight of the disproportionated rosin.

When diethanolamine, triethanolamine, n-octylamine, morpholine, andphenylguanidine are employed as and blooming agents, the amount employedwill usually be within the range of from about 2% to 15% by weight,based on the weight of the extender employed. The amount ofhexamethylenetetramine will be in excess of 2% and preferably from about3% to 15% by weight based on the weight of the extender. When a rosinamine is employed as an anti-blooming agent, the amount employed will befrom about 3% to 25% by weight, based on the weight of the extenderemployed. It is within the skill of those versed in the art, havingbefore them the teachings of this invention, to determine the optimumamount of anti-blooming agent.

The extender can be incorporated into the rubber in any suitable mannerand by any suitable means. It can be added on a rubber mill either priorto or together with other compounding ingredients. The anti-bloomingagent can be incorporated into the rubber in a manner similar to thatemployed for incorporating the extender. If desired, the anti-bloomingagent and the extender can first be thoroughly admixed and blendedtogether and the resulting blend admixed and thoroughly blended with therubber as by milling and the like. The anti-blooming agent and/or theextender can be incorporated into the rubber by addition thereof to thepolymerization reaction vessel during manufacture of a synthetic rubber.

Rosin extenders employed in this invention include the known rosinextenders for rubber. Suitable rosin extenders include natural rosin,refined or unrefined (refined rosin will usually contain, by weight,about of rosin acids and about 10% of inert material), such as naturalwood rosin, natural gum rosin, and tall oil rosin; and modified rosin,refined or unrefined, such as disproportionated rosin, hydrogenatedrosin, and polymerized rosin. The pure or substantially pure acids ofwhich rosin is comprised can be used as extenders for rubber and areconsidered, for the purpose of this invention, to be included in theexpression rosin extenders as this term is employed in the specificationand claims. The pure acids, alone or in admixture, can be used asextenders for rubber. As is well known in the art, the acids of whichrosin is comprised include abietic acid, sapinic acid, and d-pimaricacid, and these acids, as well as the other acids found in rosin, arereferred to in the art as rosin acids or resin acids. The modified formsof these pure acids or pure acid mixtures can be employ-ed as extendersfor rubber. Such modified forms include disproportionated rosin acidssuch as disproportionated abietic acid, polymerized rosin acids such asdimerized abietic acid, and hydrogenated rosin acids such asdihydroabietic 'acid and tetrahydroabietic acid.

It is well known that rosin is a mixture of isomeric rosin acids, thebest known of which are abietic acid, sapinic acid, and d-pimaric acid.The relative proportions in which these and the other isomeric rosinacids occur in a given sample of rosin depend on the source of therosin. Thus, wood rosin contains more abietic acid than any of the otheracids, while American gum rosin contains more sapinic acid, and Frenchgum rosin contains more d-pimaric acid. The several isomeric acids foundin various types of rosin can also be separated prior to modification orthe natural rosin can be refined, as by crystallization, prior tomodification.

Natural rosins, refined rosins, mixtures of pure rosin acids, or asingle pure rosin acid such as abietic acid can be polymerized by knownmethods, such, for example, as by the methods disclosed in US PatentsNos. 2,108,- 928, 2,124,675, and 2,136,525; hydrogenated by knownprocedures to produce dihydrogenated rosin and tetrahydrogenated rosin;and treated by known methods such, for example, as by the methoddisclosed in US. Patent No. 2,486,183 so that selective dehydrogenationand hydrogenation occur to produce what is refered' to in the art asdisproportionated rosin.

Disproportionated rosin is a preferred rosin extender for rubber, andthe commercially available disproportion'ated rosins will generallycontain, by weight, about 0.5% abietic acid, from about 40% to 60%dehydroabietic acid, the remainder being mostly dihydro rosin acids anda small amount of neutral materials. Disproportionated rosin can beprepared from any suitable rosin material including gum rosin, woodrosin, and tail oil rosin, and in any suitable manner as by heattreatment in the presence of a catalyst such 'as iodine, sulfur dioxide,platinum, and the like catalyst. A suitable method for effectingdisproportionation of rosin is disclosed in US. Patent No. 2,138,183.

Hydrogenated rosin which can be used as an extender for rubber is theproduct which is obtained by hydrogenating rosin as such, which consistschiefly of abietic, pimaric, sapinic, or like rosin acids or mixturesthereof, under conditions suitable to achieve saturation of at leastabout of the available two double bonds of the rosin acid radicalspresent. The term hydrogenated rosin includes similarly hydrogenatedproducts obtained from any of the group of rosin acids in substantiallypure form or mixtures of the pure rosin acids. Hydrogenated rosin can beprepared, for example, by contacting fluid, refined rosin with hydrogen,in the presence of an activated nickel catalyst, under a pressure ofabout 4000 to 5000 pounds per square inch and at a temperature of about210 C. to about 230 C. Suitable methods for producing hydrogenated rosinare described in US. Patent No. 2,094,117, reference to which is herebymade.

It is known that tall oil contains about 90% of acidic material which iscomprised of essentially equal parts of fatty acids and rosin acids.Thus, tall oil provides a source of rosin acids which can be separatedtherefrom by known procedures and modified as above. In addition,natural tall oil or refined tall oil can be employed as an extender orit can be treated so as to modify the rosin acid components thereof asset forth above.

Another suitable rosin extender for rubber is the reaction productderived from rosin and furmaric acid. A product of this type isavailable commercially under the proprietary designation Amberol 820.

A complete and comprehensive discussion of rosin and its modified formscan be found in an article by George C. Harris entitled Rosin and RosinDerivatives, Encyclopedia of Chemical Technology, vol 11, pages 779-810, December 1953, reference to which is hereby made.

In addition to use of rosin and the various modified rosins as extendersfor rubber, it has been determined that the substantially petroleumhydrocarbon-insoluble pine wood resin prepared, for example, inaccordance with the processes of US. Patent Nos. 2,193,026 and2,221,540, or equivalent processes which separate the petroleumhydrocarbon-insoluble pine wood resin from the rosin can be employed asan extender for rubber in accordance with this invention. This material,which is characterized herein by the term substantially petroleumhydrocarbon-insoluble pine wood resin, is the resinous material whichcan be prepared from pine wood by the following procedure. Pine wood,which has or has not been steamed to remove volatile constituents suchas turpentine and pine oil, can be extracted with a coal tar hydrocarbonsuch as benzol or toluol, or other suitable extraction solvent, and theextract then freed of volatile constituents, leaving a residueconsisting of a mixture of wood rosin and the resin used in the presentcomposition as a rubber extender. Extraction of this mixture with apetroleum hydrocarbon such as, for example, gasoline, dissolves andremoves the rosin. After separation of the rosin, a resinous residueremains which is low in abietic acid. Alternatively, the materialobtained on evaporation of the coal tar hydrocarbon extract can bedissolved in a mixture of furfural and a petroleum hydrocarbon such asgasoline, and the two layers which form separated, in which case thesubstantially petroleum hydrocarboninsoluble resin is found dissolved inthe furfural phase from which it can be obtained by evaporation of thefurfural. Other known methods of isolating the desired petroleumhydrocarbon-insoluble pine wood resin can be employed, if desired.

This resin is characterized by a dark brown color, cherry red solution,and by substantial insolubility in petroleum hydrocarbons, but it willvary somewhat in its specific characteristics such as acid number,melting point, exact petroleum ether solubility, and content ofn'aphthaand toluol-insoluble material, depending upon the details of theextraction processes utilized. This resin will meet substantially thefollowing specifications, namely,'substantial insolubility in petroleumhydrocarbons, substantially complete solubility in alcohol, a methoxycontent from about 3% to about 7.5% (usually from about 4% to about 6%),an acid number in the range from about to about 110, and a drop meltingpoint in the range from about C. to about C. as determined by theHercules drop method for determining the softening point of rosins andstabilized resins. This resin is a solid material of phenolic characterand comes into commerce in the pulverized or ground form, as well as inlump or aqueous emulsion form.

By chemical analysis, a typical sample of the substantially petroleumhydrocarbon-insoluble pine wood resin, prepared as hereinabovedescribed, was found to have an average molecular weight of about 450,an acid number of about 95, and an active hydrogen content, calculatedas hydroxyl and corrected for acid number, of about 56%. From thesevalues, it is calculated that there are on the average about 1.5 molesof alcoholic and phenolic hydroxyl groups and about 0.8 mole ofcarboxylic acid group per mole of resin based on 'an average molecularweight of the resin of about 450.

The synthetic rubbers that can be used as the rubber component of thecomposition of this invention are well known in the art and include thehomopolymers and copolymers derived from conjugated diene hydrocarbonssuch as butadiene-1,3, methyl-2-butadiene-1,3 (isoprene),chloro2-butadiene-1,3 (chloroprene), methyl 1 butadione-1,3(piperylene), and 2,3-dimethylbutadiene-1,3. Synthetic rubbers can bederived by copolyrnerizing any of the above compounds with up to 70% byweight of monomers that contain a vinyl group (CH =CH Examples of suchcompounds that contain a vinyl group are the aryl olefins such asstyrene, a-methylstyrene, p-chlorostyrene, dichlorostyrene,fl-methyldichlorostyrene, and vinyl naphthalene; the tit-methylenecarboxylic acids, and their esters, nitriles, and amides such as acrylicacid, methylacrylate, methylmethacrylate, acrylonitrile,methacrylonitrile, and methacrylamide; methyl vinyl ether; methyl vinylketone; vinyl pyridine; and vinylidene chloride. The butyl rubbers canbe employed in this invention also. The butyl rubbers are derived by thecopolymerization of isobutene (usually about 98% by weight) and eitherisoprene or butadiene-1,3. Examples of commercially available syntheticrubbers are neoprene, GR-M, or CR rubber (polymerizedchloro-2-butadiene- 1,3). Buna S, GR-S, or SBR rubber (a copolymer ofbutadiene-1,3 and styrene), Buna N, GR-A, or NBR rubber (a copolymer ofbutadiene-LB' and acrylonitrile), and GR-I or HR (a copolymer ofbutadiene-1,3, and isobu tene or a copolymer of isoprene and isobutene).

A preferred synthetic rubber for use in this invention is a syntheticpolybutadiene containing at least about 75 percent butadiene joinedtogether by cis-1,4 linkage. The cis-polybutadienes can be produced byany of the known polymerization processes which yield predominantly cis-1,4 butadiene polymers. The cis 1,4 polybutadienes which can be employedin this invention will have a viscosity between 40 and 150 and higher ifdesired as meas ured on the Mooney viscosimeter at 212 F. (ML-4). A morepreferred range of Mooney viscosity is from 80 to 150. The polybutadieneis one in which at least about 75 percent and up to 100 percent,preferably 85 to 98 percent, of the polymer is formed by cis-1,4addition of the butadiene, the remainder of the polymer being formed bytrans-1,4 and 1,2 addition of the butadiene.

Another suitable synthetetic rubber is a synthetic polybutadienecontaining from about to buta-diene joined together by cis-1,4 linkageand the remainder of the polymer being formed by trans-1,4 and 1,2addition of the butadiene, the polymer being characterized bysubstantially regular repetition of the cis and trans configurations inthe polymer chain. These polymers will have a viscosity between aboutand 150 as measured on the Mooney viscosimeter at 212 F. (ML-4).

Known extending oils can be incorporated into the novel compositions ofthis invention if desired. The extending oils which can be used cover awide range of oils having various chemical and physical properties. Anyof the well-known oils that are compatible with rubber, ranging fromvery light to very viscous, can be used as extending oils in accordancewith well-known practices.

Whitby (Synthetic Rubber, page 219, John Wiley & Sons, 1954) indicatesthat extender oils can be divided into three broad classes, namely,naphthenic, aromatic, and highly aromatic. For non-discoloring rubbers,naphthenic oils are usually employed, while aromatic and highly aromaticoils are preferred for discoloring rubbers. Thus, suitable extended oilsinclude pine tar, light lubricating oils, and the like. Circosol 2Xl-I(a proprietary designation) is a light lubricating oil fully describedin Rubber Age, vol. 70, No. 6, pages 735-747, March 1953, and is aparticularly suitable extender oil. Circosol 2XH contains hydrocarbonsof high molecular weight, in the form of a heavy, viscous, transparent,pale green, odorless liquid of low volatility; it has a specific gravityof 0.940, and a Saybolt Universal viscosity at 100 F. of about 2000seconds. Other extender oils are disclosed and described in US. PatentNo. 2,964,083. The amount of extender oil employed will be form about 15to 150 parts by weight for each 100 parts by weight of rubber component.

The usual fillers, reinforcing agents, antioxidants, vulcanizers,extenders, plasticizers, softeners, processing aids, as well asactivators and accelerators well known in the preparation of naturalrubber and synthetic rubber compositions, can be employed in accordancewith this invention.

Fillers that can be employed include aluminum flake, antimony sulfide,asbestos, barium sulfate, cadmium sulfide, appropriate grades of carbonblack, chromic oxide, clay, such as bentonite, cotton linters, ironoxide, lime, litharge, lithopone, magnesium carbonate, magnesium oxide,silica, slate flour, talc, titanium oxide, whiting, zinc oxide, zincsulfide, and the like. Zinc oxide, reinforcing grades of carbon black,hydrated silica, calcium carbonate, and the like, can be employed asreinforcing agents. Suitable pigments, such as ultramarine, Vermilion,or the like, can be employed to impart to the composition a -de siredcolor.

The vulcanizing agent which is employed preferably is sulfur. However,in certain cases, selenium or tellurium can be employed either alone orin conjunction with sulfur in order to obtain certain modifications ofthe characteristics of the composition in respect to the vulcanizationprocess. In the event that the traces of these vulcanizing agents mightbe objectionable in the vulcanized product, a peroxide vulcanizing agentsuch as benzoyl peroxide, dicumyl peroxide, and the like, can beemployed.

As a means for obtaining vulcanization of the composition at lowertempeartures or for increasing the rate of vulcanization, suitableaccelerators can be employed. Accelerators which are familiar to the artare, in general, satisfactory. Thus, suitable accelerators include2-mercaptobenzothiazole, N-oxydiethylene benzothiazole-Z-sul fenamide,cli-o-tolyl guanidine, ethylidine guanidine, hexamethylenetetramine,methylene aniline, tetramethyl thiuram disulfide, thiocarbanilide,diphenylamine, diphenyl guanidine, tetramethylthiuram monosulfide,triethyltrimethylenetriamine, and the like. The effects of these variousaccelerators and of accelerators which are equivalent thereto, upon thevulcanization of the composition and upon its properties aftervulcanization may vary somewhat, in a manner known to the art, andthereby provide means for controlling certain of the properties of thevulcanized product. Although the additional control of thecharacteristics may be desirable in certain circumstances, in generalthe use of Z-meraptobenzothiazole or of N-cyclohexyl-Z-benzothiazolesulphenamide has been found to be preferable.

The following examples will illustrate this invention more fully. In theexamples, all parts and percentages are by weight unless otherwiseindicated.

Example 1 The following composition was milled at a temperature of about212 F. to provide a vulcanizable, substantially homogeneous mass, andwas subsequently vulcanized for 60 minutes at a temperature of 295 F.under a pressure of about 700 psi.

Component: Parts Cis-1,4-polybutadiene, Mooney value of 42 (ML-4 at 212F.), cis-1,4 addition,

Disproportionated wood rosin 25 Naphthenic oil, processing aid (Circosol2XH) l0 HAF carbon black (Vulcan 6) 50 Mixture of diaryl pphenylenediamines, antioxidant (Wingstay 1 Stearic acid (Stearex Beads)2 Zinc oxide (Horsehead XX4) 3 N-oxydiethylene benzothiazole 2sulfenamide plus a small percentage of benzothiazyl disulfide,accelerator (Amax No. 1) 0.75 Sulfur 2.5

' The vulcanizate had fair building tack. The vulcanizate was aged in anair oven maintained at a temperature of about 212 F. for a period ofabout 48 hours, and an examination of the aged vulcanizate indicatedexudation of a substantial portion of the disproportionated rosincomponent.

Example 2 Example 1 was repeated with the exception that the ture ofabout 212 F. to provide a viscous, substantially homogeneous,vulcanizable mass which was subsequently vulcanized at 295 F. under apressure of about 700 p.s.i. for 60 minutes.

coirtlposltlion ctontialnfegs22 giartsf sulfur tl nsteaddof 2.(51component: Pam pa an 2 9 f 9 y Cis-1,4-polybutadiene, Mooney value of 42as 1 gi 9 2 d (ML-4 at 212 F.),cis-1,4 addition, 90-92% 50 e g ame rt i1 P 2; e t L f Natural rubber (No. 1 smoked sheets) 50 rosm an Pa 0 anoamme' m mg d 0 1 Naphthenic oil, processing aid (Circosol 2XH) thevulcanizate was good and there was no exudation or 10 b1 f th t d d f mhCarbon black (Vulcan 6) 50 i i 0 f e lspmpor Iona 6 W00 Tosm mm 6Mixture of diaryl p phenylenediamines, anti- Vu Camzat a aglngoxidant(Wingstay 10g 1 Stearic acid (Stearex Beads) 2 Examp 3 Zinc oxide(Horsehead XX4) 3 Example 1 was repeated wlth the exception that the Noxydiethylene benzothiazole-Z-sulfenamide composition used contained 2.1parts of sulfur instead plus a small percentage of benzothiazyl of 2.5parts, and the composition contained, instead of disulfide, accelerator(Amax No. 1) 0.75 parts of disproportionated wood rosin, 23.75 parts ofSulfur 1.4 disproportionated wood rosin and 1.25 parts of triethanol- 2Oamine. Building tack of the vulcanizate was good, and Example 7 therewas no exudation of the disproportionated wood rosin from thevulcanizate after aging. Example 6 was repeated except that 1.5 parts ofsulfur was employed instead of 1.4 parts, and 100 parts of the Example 4cis-1,4-polybutadiene was employed as the rubber component of thecomposition in place of the 50 parts of cis- Example 1 was repeatedexcept that the colnposltlon 1,4-polybutadiene and 50 parts of naturalrubber as emcontained 2 parts sulfur instead of 2.5 parts and conployedin Example 6. tained 23.5 parts of disproportionated wood rosin and 1.5parts of triethanolamine. There was no exudation of dis- 0 Example 8 roortionated wood rosin after a in 3 p P g Example 6 was repeated exceptthat 2.4 parts of sulfur Example v was used in the composition, 66.6parts of the cis-1,4 olybutadiene was used as the rubber component inlace P P Example 1 was repeated with the exception that the of thenatural rubber-polybutadiene rubber component composition contained inaddition to the components 1n of Example 6, and there was incorporatedseparately into Example 1 1.25 parts of trlethanolamine. The composithecomposition 33.3 parts of disproportionated wood tlon had goodprocessabillty at 212 F. and had fair buildrosin and 3 parts oftriethanolamine (about 8.35% of ing tack. There was no exudatlon orblooming of the distriethanolamine, based on the disproportionated woodproportionated wood rosin from the vulcanizate after rosin). a e

Table I below shows a comparison of certain physical Examp 1e 9properties of the vulcanizates of Examples 1, 2, 3, 4, and Exam ple 8was repeated w th the exceptlon that the g q t pliysufal propemes.of idisproportionated wood rosin (33.3 parts) and the trig i i gi g g 5.ethanolamine (3 parts) were thoroughly admixed to prop e w 6 W W 1 6 iammg vide a substantially homogeneous blend prior to incorproportlonatedwood rosln, contained no trlethanolamlne.

poratlon into the composition. Aglng of the vulcanlzates was done in acirculating an oven at 212 F. for 48 hours.

Example 10 TABLE I E 1 N 00 Example 7 was repeated except that thecomposltlon e 0 1 2 3 4 5 contained 66.7 parts of thecis-l,4-polybutadiene instead Tensile Srength, p.s.i. of 100 parts andcontained, in addition to the other coms gi L gg 'gggg 3'125 3225 3,300ponents of Example 6, 33.3 parts of disproportionated a lene StrengthAfter wood rosin. The disproportionated wood rosin exuded 88 91 94 96 92from the vulcanizate after aging. m g gx p p h 480 560 6 600 580 TableII below gives certain physical properties of the itfgfi gfiglggg 57 6671 76 7O vulcanizates of the above Examples 6, 7, :8, 9, and 10. Unlessotherwise indicated, oven aged refers to heating E 1 6 the vulcanizatesin a circulating air oven maintained at a Xamp e temperature betweenabout 212 F. to 220 F. for a peri- The following composition was milledat a tempera- 0d of about 48 hours.

TABLE II Example No 6 7 8 9 10 Mill Processing at 212 F Dry BuildingTack 1 Exudation of Rosin Component After Being Oven Aged No No Y MooneyViscosity ML-4 212 F 60 32 38 40 Specific Gravity (Vulcanized) 1.1041.106 1.158 1.153 1.155 Modulus at 300% Elong, p.s i 1, 040 825 1, 1,1601, 240 Oven Aged 1,070 1,300 2,320 2,155 2,550 Percent Retention AiterAmg 230 208 205 Tensile Strength, p.s.i.,25 0 3, 290 3, 200 3,190 3,0303,200 Oven Aged 2,430 3,140 3,300 2,860 2,550 Percent Retention AfterAging 74 95 103 94 79 Elongation at Break, Percent, 25 C 620 690 620 610640 Oven Aged 380 400 405 395 30 Percent Retention After Aging 61 58 6565 7 Shore A Hardness, 25 0 55 53 55 60 61 Oven Aged 63 67 64 68 66TABLE II-Continued Example No Ozone Resistance at 95-100 F., MinutesRequired to Produce First Cracks -10 1 Good.

2 Poor.

8 Fair.

4 Excellent.

5 Samples were air oven aged 54 hrs. at 212 F.

Looped samples (Static) Ozone concentration 100+ parts per 100 million.Observations for cracking were made under 5X magnification.

It will be noted from Table II above that the disproportionatedrosin-triethanolamine modified rubber compositions of Examples 8 and 9show all-around equivalence with the unmodified composition of Examples'6 and 7 with distinct superiority in certain properties. Especially forpassenger tire tread application, the low Yerzley resilience and goodheat build-up resistance of the Vulcanizates of Examples 8 and 9 is adesirable combination of properties which give good ride (rumbleabsorption) and a low squeal, without incurring excessive heat build-up.

The wear-resistant properties of tire treads prepared 7 o from thecompositions of Examples 6 and 8 were determined by actual road testsusing miniature tires on towjigs as described in Proceedings,International Rubber Conference, Washington, DC, November 1959, page 95.Tire treads prepared from the Example 8 composition (average for fourtest tires) gave 57% more mileage than those prepared from the Example'6 composition (average for four test tires).

The following examples, set forth in tabulated form in Table III belowshow the utility of various types of extenders, including rosinextenders, that are applicable for use in carrying out this invention.The composition employed in the examples consisted of the followingcomponents in the amounts set forth.

Component: Parts Mixture of diaryl-p-phenylenediamines, antioxidant(Wingstay 100) 1.0 Stearic acid (Stearex Beads) 2.0 Zinc oxide 3.0

N oxydiethylene benzothiazole-Z-sulfenamide plus a small percenatge ofbenzothiazyl disulfide, accelerator (Amax No. 1) 0.75 Sulfur 2.4

The specific extender or extender plus triethanolamine (anti bloomingagent) employed in each example is set forth in the table. In the tableB.B.A. stands for blended before adding, which means that the extenderand the triethanolamine were blended prior to incorporation into thecomposition, and LS. stands for incorporated separately, which meansthat the extender and the triethanolamine component were incorporatedinto the composition separately. Vulcanizates were prepared from eachcomposition by first milling the composition at a temperature of about212 F. to provide a workable, viscous, substantially homogeneous massand subsequently heating the mass at a temperature of about 295 F.,under a pressure of about 700 p.s.i. for about minutes. Aging of thevulcanizates was accomplished in a circulating air oven maintained at atemperature of about 212 F. for a period of 24 hours.

and Rosin Acids.

Component: Parts Cis-1,4-polybutadiene, Mooney value of 42 (ML-4 at 212F.), bis-1,4 addition, 90

92% 66.7 Extender or extender plus treithanolarnine 33.3

Naphthenic oil, processing aid (Circosol 2XH) 10.0

TABLE III Parts of Parts of Mill Buildin Tensile Exudation Example No.Extender Extender Triethanolamine Processing Tack g Strength After Oven1 (p.s.i.) Aging 1 3,090 No.

3, 260 Yes. 2, 505 No.

,130 Yes. o a 17 Pine Wood Resin Substantially Insoluble in iseg Nr fPetroleum Hydrocarbons. 13 Rosin-Furnarie Acid Adduct 2,135 No. 19 WoodRosin l ,575 No. 20 Disproportionated Tall 00.. 2, 360 No. 21 Disroportionated Blend (22:1) of Fatty Acids 2,420

The examples summarized in Table IV below illustrate the use of variousamines as anti-blooming agents to prevent exudation of a rosin extenderfrom a rosin-extended rubber composition. The composition employed inthese examples consisted of the following components in the Carbon black(Vulcan 6) 50.0 amounts specified.

1 1 Component: Parts Cis-1,4-polybutadiene, Mooney value of 42 (ML-4 at212 F.), cis-1,4 addition, 90-92%, rubber component See Table IV.Disproportionated wood rosin plus anti-blooming agent See Table IV.Naphthenic oil, processing aid (Circosol 2XH) 10. HAF carbon black 50.Mixture of diaryl p phenylenediamines, antioxidant (Wingstay 100) 1.Stearic acid (Stearex Beads) 2. Zinc oxide 3. N oxydiethylenebenzothiazole-Z-sulfenamide plus a small percentage of benzothiazyldisulfide, accelerator (Amax No. 1) 0.75. Sulfur 2.4.

Vulcanizates were prepared from each composition by heating and millingthe composition to provide a viscous, workable, substantiallyhomogeneous rubber mass and subsequently vulcanizing the mass under apressure of about 700 psi. at a temperature of about 212 F. for a periodof about 60 minutes. Aging of the vulcanizates was accomplished in acirculating air oven maintained at a temperature of about 212 F. for 24hours. LS. and B.B.A. have the same meaning as in Table III.

TABLE IV 12 Component Parts Mixture of diaryl-p-phenylenediamines,antioxidant (Wingstay 100) 1 Stearic acid (Stearex Beads) 2 Zinc oxide 3N-oxydiethylene benzothiazole 2 sulfenamide plus a small percentage ofbenzothiazyl disulfide, accelerator (NOBS special) 0.75 Sulfur 2.1

10 The processing properties of this composition were good, the Mooneyviscosity ML-4 at 212 F. was 40, and the Mooney Scorch at 270 F.min./5-pt. rise was 19.

Example 28 Example 27 was repeated with the exception that thecis-1,4-polybutadiene was replaced with a higher viscositycis-1,4-polybutadiene having a Mooney viscosity ML-4, 212 F., of about110 and a cis-1,4 content of 90-92%. The processing properties of thiscomposition were excellent, the Mooney viscosity ML-4 at 212 F. was 50,and the Mooney Scorch at 270 F. min./5-pt. rise was 14.

Example 29 Example 27 was repeated with the exception that 100 parts ofan oil-extended, high-viscosity cis-1,4-polybutadiene having a Mooneyviscosity ML-4, 212 F., of was used as the rubber component, and norosin extender was used to extend the rubber component nor was there anytriethanolamine present in the composition. The oil-extendedcis-1,4-polybutadiene employed consists of,

Anti- I Example No. Anti-Blooming Agent Blooming Disproportionated AgentParts Wood Rosin Parts Rubber Process- Exuda- Tensile Compoing Buildingtion After Strength nent; Proper- Tack Cure (p.s.i.) Parts ties Example27 The following composition was prepared.

Component: Parts Cis-1,4-polybutadiene, Mooney viscosity of 42 (ML-4 at212 F.), cis-1,4 addition, 90-

by weight, 33 /a% naphthenic process oil and 66%% ofcis-1,4-polybutadiene having a Mooney viscosity ML-4, 212 F., of about100 and a cis-1,4 addition of about 96-97% This oil-extendedpolybutadiene is available commercially under the proprietarydesignation Ameripol 442. Processing properties of this composition werepoor, the

92%, rubber component 67 45 Money viscosity ML-4 212 F. was 43, andMooney Disproportlonated wood rosln plus 5% tri- Scorch at 270 F.m1n./5-pt. rise was 34.

ethanolamlne 33 In Table V below there are set forth certain propertiesHAF carbon black of the compositions of Examples 27, 28, and 29. AgingNaphthemc oil, processmg aid (C1rcosol was done 1n a circulating an ovenat a temperature of ZXH) 10 about 212 F. for about 48 hours.

TABLE v Vulcanlzing Example 27 Example 28 Example 29 Time at 298 F.Unaged Aged Unaged Aged Unaged Aged (Minutes) 20 255 240 210 30 265 245225 Modulus at p.s.i 45 240 410 255 340 230 423 60 295 225 225 215 230200 20 1, 040 1, 240 330 30 935 1,330 1,085 Modulus at 300%, .s.l 451,020 1, 742 1,150 1, 050 1,095 1, 073

60 1, 050 1,150 1,175 120 340 1,050 840 20 3, 090 2, 885 1, s50 30 2,8853, 200 1, 450 Tensile Strength, p.s.l 45 3,180 2,845 3,045 2,815 1, 0801, 270

50 3, 345 3, 1, 330 120 3, 3,325 1, 510 20 370 575 500 30 555 550 385Elongation, percent 45 675 435 605 430 410 217 50 715 540 320 120 750550 425 20 54 55 47 30 54 55 49 Shore A2 Hardness 45 53 61 54 62 50 5450 55 54 50 120 55 53 4s 20 20 20 15 30 2o 20 10 Break Set, Percent 4530 15 20 10 10 0 so 35 20 10 120 20 20 10 Relative Wear Resistance,percent 124 132 100 Example 28 utilizes a higher viscositycis-1,4-polybutadiene which is used in oil-extended polybutadiene. Asthe TABLE VI Example No. Minutes Vulcanized 30 31 32 33 7. 475 1, 500Marlowe... 3 33 1;;33 gg 60 1, 115 1, 100

7. 5 675 690 Elongation at Break, percent g8 gg fig gg 21g 60 615 600 7.5 39 56 Shore A Hardness g; 60 4G 49 7. 5 Yes N o Exndatlon on Aging 24hrs. at 212 F- g3 38 30 Yes Slight test data in Table V show, the higherviscosity poly- Example 34 butadiene provides a rosin-extended productwith better processing characteristics than either regular viscositypolybutadiene with rosin extender (Example 27) or high viscositypolybntadiene with oil extender (Example 29). The low tensile strengthof the commercial oil-extended product should be noted especially asWell as the 32% better wear resistance of the rosin-extended highviscosity cis-l,4-polybutadiene compared with the oil-extended cis-1,4-polybutadiene.

Example 30 A composition consisting of the following components wasprepared and milled at 212 F. to provide a workable, viscous,homogeneous, vulcanizable rubber composition.

rosin) Example 31 A vulcanizable rubber composition was prepared usingthe components of Example 30 with the exception that the rosin componentused was a blend of 19 parts of disproportionated wood rosin and 1 partof triethanolamine.

' Example 32 A vulcanizable rubber composition was prepared using thecomponents of Example 30 except that 40 parts of disporportionated woodrosin was employed instead of the parts of Example 30.

Example 3 3 A vulcanizable rubber composition was prepared using thecomponents of Example except that the rosin component used was a blendof 38 parts of disproportionated wood rosin and 2 parts oftriethanolamine.

The vulcanizable natural rubber compositions of Examples 30, 31, 32, and33 were vulcanized at 293 F. under a pressure of 700 p.s.i. for variousperiods of time.

A butadiene-styrene rubber composition was prepared from the followingcomponents.

Components: Parts GR-S X-732 86 Disproportionated wood rosin 14 HAFcarbon black 50 Zinc oxide 5 Stearic acid 2 N-cyclohexyl-2-benzothiazolesulfenamide, ac-

celerator (Santocure) 1 Sulfur 1.75

GRS X732 is a rosin-extended butadiene-styrene co polymer comprised of73% of a high-viscosity butadienestyrene copolymer and 27%ofdisproportionated wood rosin. The processability of this composition onmill rolls at room temperature was good. The tensile strength of thevulcanizate (press cured under 700 p.s.i. for 60 minutes at 300 F.) was3,035 p.s.i. The vulcanizate was heated in an air oven for 24 hours at212 F., and resin exudation was observed.

Example 35 Example 34 was repeated except that 3.6 parts oftriethanolamine was incorporated into the composition. Theprocessability of the composition on mill rolls at room temperature wasgood, and the tensile strength of the vulcanizate was 3,760 p.s.i. Therewas no evidence of resin exudation after heating the vulcanizate in anair oven for 24 hours at 212 F.

Example 36 A vulcanizable rubber composition comprised of the fol lowingcomponents was prepared.

Components: Parts Cis-l,4-polybutadiene having a Mooney viscosity ML-4212 F. of 110 and cisl,4 addition content of 90-92% 67 Blend consistingof, by weight, disproportionated wood rosin and 5% triethanolamine 24.7Naphthenic oil (Circosol NS) 8.3 Naphthenic oil (Circosol 2XH) 10.0Carbon black (Philblack O) 50.0 Zinc oxide (XX-4) 3.0 Stearic acid(Stearex Beads) 2.0 Mixture of diaryl-p-phenylenediamines, antioxidant(Wings'tay 1.0 N-oxydiethylene benzothiazole-Z sulfenamide,

accelerator (NOBS special) .75 Sulfur 2.1

Circosol NS is a light-colored, nonvolatile naphthenic oil having aspecific gravity at 60 F. of 09279, a Saybolt Universal seconds (SUS)viscosity at 100 F. of 781, an

16 Component: Part by weight Cis-1,4-polybutadiene, Mooney value of 42(ML-4 at 212 F.), cis-1,4-addition, 90

SUS viscosity at 210 F. of 61, a flash point of 395 F., 92% 67 a firepoint of 445 F., a pour point of 5 F., an aniline 5 Disproportionatedwood rosin plus 5% hexapoint of 179 F., a refractive index of 1.5085,and a methylenetetramine (melt blended) 33 viscosity gravity constant of0.870. It contains 18% aro- Carbon black (Vulcan 6) 5O matic carbonatoms, 39% naphthenic carbon atoms, and N h h i il, processing id (Cir12XI-1) 10 43% Palflfliflic carbon atoms. Mixture ofdiaryl-p-phenylenediamines, antioxi- 10 dant (Wingstay 100) 1 Example 37Stearic acid (Stearex Beads) 2 Zinc oxide (Horsehead XX4) 3 Example Wasep Wlth the F QP that 22 N-oxydiethylene benzothiazole-2-sulfenamideparts of the disproportionated wood rosin-trlethanolamme l smallpercentage of b hi l di. blend was used and 11 parts of C1rc0sol NS wasused. 15 ulfid accelerator (Amax 1 75 Sulfur (Tube brand) 2.4 Example 38Vulcamzates were prepared from the above composi- Example 36 wasrepeated with the exception that 16.5 tion by vulcanizing for 60 minutesat a temperature of parts of the dispr-oportionated woodrosin-triethanolamine 298 F. under a pressure of about 700 p.s.1. Agingof blend was used and 16.5 parts of Circosol NS was used. thevulcanizates at 212 F. for hours and for 16 In Table VII below there areset forth properties of hours at 300 F. showed no exudation of thedisproporvulcanizates prepared from the compositions of Examplestionated wood rosin. 36, 37, and 38. The compositions of this inventioncan be used in the TABLE VII Example 36 Example 37 Example 38 MooneyViscosity ML-4 212 F.

Minutes 39 39 39 Cured Scorch at 270 F., Min. to 5 pt. rise Unaged Aged2 Unaged Aged 2 Unaged Aged 2 20 325 490 350 610 30 375 650 340 575 100%Modulus, p.s.i 380 500 320 555 60 325 535 350 555 120 300 430 320 005 201,590 30 1,920 300% Modulus, p.s.i 45 1, 680 1,070 120 1,620 20 2, 25030 2,400 Tensile Strength, p.s.l 45 2, 720 50 2, 425 120 2, 415 1, 9302,030 2, 055 20 330 150 335 195 30 375 200 305 175 Elongation, percent45 440 215 325 205 50 400 235 350 230 120 410 250 333 245 20 61 71 e0 70a0 61 53 e1 70 Shore A2 Hardness 45 61 69 68 50 50 e9 53 67 120 5s 54 5755 20 10 10 5 10 30 5 10 5 10 Break Set, percent 45 10 10 5 10 00 7 10 510 120 10 10 5 10 Heat Build-Up, AT F. (212 F.) 8 8 Relative WearResistance 118 100 1 Press cured at 298 F. under a pressure of 700p.s.i. 2 Air Oven Aged 48 Hours at 212 F. 1 Cylinders cured minutes/298.

EXAMPLE 39 The following composition was milled at a temperature ofabout 212 F. to provide a vulcanizable, substantially homogeneous mass.

manufacture of tire treads having excellent wear-resistant properties.They can be used also in the manufacture of rubber belts, rubber floormats, rubber impact pads, and the like, where high resistance to wear isrequired.

It is to be understood that the above description and examples areillustrative of this invention and not in limitation thereof.

What I claim and desire to protect by Letters Patent is:

1. A vulcanizable composition comprising (A) a rubber component selectedfrom the group consisting of (1) natural rubber, (2) apolybutadiene-styrene copolymer, (3) a polybutadiene formed by cis-1,4-,trans-1,4-, and 1,2-addition of 1,3-butadiene, at least about 17 75% ofthe polybutadiene being formed by cis- 1,4-addition of 1,3-butadiene and(4) mixtures thereof,

(B) an extender for the rubber component selected from the groupconsisting of a rosin extender, a substantially petroleumhydrocarbon-insoluble pine wood resin, and mixtures thereof in an amountof from about 20 parts to 100 parts by weight for each 100 parts byweight of rubber component, and

(C) a material selected from the group consisting of diethanolamine,triethanolamine, n-octylamine, morpholine, hexamethylenetetramine,diphenylguanidine, a rosin amine, and mixtures thereof in an amount offrom about 2% to 25% by weight based on the weight of extender.

2. A vulcanizable composition in accordance with claim 1 wherein rubbercomponent (A) is a butadienestyrene copolymer,

3. A vulcanizable composition in accordance with claim 1 wherein rubbercomponent (A) is a poly butadiene formed by cis-1,4-, trans-1,4-, and1,2addition of 1,3- butadiene, at least about 75 of the polybutadienebeing formed by cis-l,4-addition of 1,3-butadiene.

4. A vulcanizable composition in accordance with claim 1 wherein rubbercomponent (A) is natural rubber.

5. A vulcanizable composition comprising (A) a rubber component selectedfrom the group consisting of (1) natural rubber,

(2) a butadiene-styrene copolymer,

(3) a polybutadiene formed by cis-l,4-, trans-1,4-, and 1,2-addition of1,3-butadiene, at least about 75 of the polybutadiene being formed bycis- 1,4-addition, of 1,3-'butadiene and (4) mixtures thereof,

(B) disproportionated rosin in an amount of from about 20 parts to 100parts by weight for each 100 parts by weight of rubber component, and

(C) triethanolamine in an amount of from about 2% to 15% by weight basedon the weight of disproportionated rosin.

6. A vulcanizable composition in accordance with claim 5 wherein rubbercomponent (A) is a polyhutadie'ne formed by cis-l,4-, trans-1,4-, and1,2-addition of 1,3- butadiene, at least about 75 of the polybutadienebeing formed by cis-1,4-addition of 1,3-butadiene.

7. A vulcanizable composition comprising (A) a rubber component selectedfrom the group consisting of (1) natural rubber,

(2) a butadiene-styrene copolymer,

(3) a polybutadiene formed by cis-1,4-, trans- 1,4-, and 1,2-addition of1,3-butadiene, at least about 75% of the polybutadiene being formed bycis-1,4-addition of 1,3-butadiene and (4) mixtures thereof,

(B) hydrogenated rosin in an amount of from about 20 parts to 100 partsby weight for each 100 parts by weight of rubber component, and

(C) triethanolamine in an amount of from about 2% to 15% by weight basedon the weight of hydrogenated rosin.

8. A vulcanizable composition in accordance with claim 7 wherein rubbercomponent (A) is a polybutadiene formed by cis-l,4-, trans-1,4-, and1,2-additin of 1,3-butadiene, at least about 75% of the polybutadienebeing formed by cis-1,4-addition of 1,3-butadiene.

9. A vulcanizable composition comprising (A) a rubber component selectedfrom the group consisting of (1) natural rubber,

(2) a butadiene-styrene copolymer,

(3) a polybuta-diene formed by cis-l,4-, trans- 1,4-, and 1,2-additionof 1,3-buta-diene, at least about of the polybutadiene being formed bycis-l,4-addition of 1,3-butadiene and (4) mixtures thereof,

(B) polymerized rosin in an amount of from about 20 parts to parts byweight for each 100 parts by weight of rubber component, and

(C) triethanolamine in an amount of from about 2% to 15% by weight basedon the weight of polymerized rosin.

10. A vulcanizable composition in accordance with claim 9 wherein rubbercomponent (A) is a polybutadiene formed by =cis-1,4-, trans-1,4-, and1,2-addition of 1,3- butadiene, at least about 75 of the polyhutadienebeing formed by cis-l,4-addition of 1,3-butadiene.

11. A vulcanizable composition comprising (A) a rubber componentselected from the group consisting of (1) natural rubber,

(2) a butadi'ene-styrene copolymer,

(3) a polybuta-diene formed by cis-1,4-, trans- 1,4-, and 1,2-additionof 1,3-butadiene, at least about 75 of the polybutadiene being formed bycis-1,4-addition of 1,3-butadiene and (4) mixtures thereof,

(B) a substantially petroleum hydrocarbon-insoluble pine wood resin inan amount of from about 20 parts to 100 parts by Weight for each 100parts by weight of rubber component, and

(C) .triethanolamine in an amount of from about 2% to 15% by weightbased on the weight of the substantially petroleum hydrocarbon-insolublepine wood resin.

12. A vulcanizable composition in accordance with claim 11 whereinrubber component (A) is a polybutadiene formed by cis-1,4-, trans-1,4-,and 1,2-ad-dition of 1,3-butadiene, at least about 75 of thepolybutadiene being for-med by cis-1,4-ad'dition of 1,3-butadiene.

References Cited UNITED STATES PATENTS 2,491,913 12/1949 Amberg 260-272,784,165 3/1957 Howland 260-27 2,829,121 4/1958 Leeper 26045.92,881,096 4/ 1959 Kisbany 260-27 2,894,924 7/ 1959 Rockoff 260273,060,989 10/1962 Railsback et al. -152330 3,157,609 11/1964 McNay et a126027 OTHER REFERENCES l. Compounding Ingredients for Rubber, compiledby Editors of Rubber World, 3rd edition, 1961, pp. 11, 37, 38, 40, 67,75, 87 and 341, copy available in Scientific Library (TS 1890.153).

2. Amberg, Rubber Age, Hydrogenated Rosin in Cold Rubber Tire TreadStocks, vol. 69, May 1951, pp. 191- 199, copy available in ScientificLibrary (TS 1870.116).

3. Rosin Amine D, Bulletin of Hercules Powder Co., Bulletin No. 5044,November 1952, pp. 3, 25, and 26, copy available in Group 141.

DONALD E. CZAJA, Primary Examiner.

F MCKELVEY, Assistant Examiner.

